The US Department of the Treasury is reviewing licenses for Boeing Co. and Airbus to sell Iran aircraft, while it will do its best to impose “additional sanctions” on Tehran.

Treasury Secretary Steven Mnuchin made the comments before a House of Representatives panel Wednesday.

“We will use everything within our power to put additional sanctions on Iran, Syria and North Korea to protect American lives,” he told members of the House Ways and Means Committee.

Officials in the administration of US President Donald Trump have been sparing no efforts to undermine the nuclear deal between Iran and the world powers, including the US, as it was negotiated in the administration of President Barrack Obama.

“I can assure you that’s a big focus of mine and I discuss it with the president,” Mnuchin told lawmakers.

Most of Iran’s aging fleet of 250 commercial planes were purchased before 1979, and as of June 2016, only 162 were operational, with the rest grounded because of a lack of spare parts.

Airlines in Iran have been operating for decades on ageing fleet of Boeing and Airbus airliners, plus some Russian planes bought or leased since the revolution.

Iran and the world powers – the US, Britain, Russia, Germany, china and France – reached a nuclear deal in Vienna in July 2015.

Under the Joint Comprehensive Plan of Action (JCPOA), Iran undertook to put limitations on its nuclear program in exchange for the removal of nuclear-related sanctions imposed against Tehran.

Trump has been a staunch opponent of the Iran nuclear deal as it was negotiated under his Democratic predecessor despite the Republican Party’s opposition.